CN106926045B

CN106926045B - Tool holder turret with coaxial brake

Info

Publication number: CN106926045B
Application number: CN201610862668.6A
Authority: CN
Inventors: 弗兰科·德贝尔纳迪
Original assignee: DUPLOMATIC AUTOMATION Srl
Current assignee: DUPLOMATIC AUTOMATION Srl
Priority date: 2015-09-28
Filing date: 2016-09-28
Publication date: 2020-06-26
Anticipated expiration: 2036-09-28
Also published as: CN106926045A; KR102579364B1; TWI697377B; EP3150331A1; KR20170037840A; TW201711786A; ITUB20153942A1; EP3150331B1

Abstract

A tool holder turret wherein a single electric servo motor is designed for locking and unlocking a tool holding plate and for imparting angular displacement to the tool holding plate to change the tool position. The tool holder turret comprising: a stationary base body, a tool holding disk, a first cylindrical annular body with a cam follower, a second cylindrical annular body with a cam profile, a locking member, and an electric servo motor kinematically connected to the second cylindrical annular body to impart an angular displacement to the second cylindrical annular body in two rotational directions coaxial with the shaft; the cam follower and the cam profile cause the first cylindrical annular body to move axially in both directions on the shaft due to the angular displacement of the second cylindrical annular body; furthermore, the first cylindrical annular body is kinematically connected to an auxiliary shaft coaxial with the aforementioned shaft and has braking means to lock the rotation of said first cylindrical annular body when activated.

Description

Tool holder turret with coaxial brake

Technical Field

The present invention relates to a tool holder turret of the type comprising: a fixed base body having a cavity extending along a longitudinal axis (X-X); a tool holding disk rotatable in two directions of rotation relative to the fixed base body about an axis of rotation, which is coaxial and coincident with the longitudinal axis (X-X), the tool holding disk being mounted to the end of a shaft extending along the longitudinal axis (X-X); a first cylindrical annular body keyed to the shaft and free to slide axially on the shaft only between a first axial position and a second axial position against elastic means acting between the first cylindrical annular body and the tool-holding disk; a second cylindrical annular body also keyed to the shaft and rotatable relative to the shaft, the second cylindrical annular body having a plurality of symmetrical cam profiles disposed on a circumference of a front surface of the second cylindrical annular body relative to a proximal end of the tool gripping disk; a locking member for locking said tool holding disk relative to said fixed base body when said first cylindrical annular body is in its first axial position and for unlocking said tool holding disk when said first cylindrical annular body is in its second axial position, said first cylindrical annular body having a plurality of cam followers, the front portions of which engage corresponding symmetrical cam profiles of said second cylindrical annular body, said cam followers and said cam profiles causing axial movement of said first cylindrical annular body on said shaft in both directions due to angular displacement of said second cylindrical annular body; an electric servo motor kinematically connected to the second cylindrical annular body to impart an angular displacement to the second cylindrical annular body in two directions of rotation coaxial to the shaft.

Background

Tool holder turrets of the above type are known in the prior art.

For example, as described in IT 1,138,598, IT uses a motor that unlocks and locks a tool holding disk to a turntable body by a suitable mechanism having a cam profile to rotate the tool holding disk for tool replacement.

The same motor also provides angular displacement of the disc to change the position of the tool used.

These turntables therefore have the advantage of using a single energy source for their operation, i.e. electrical energy, and of using a single motor for all movements.

Such a turntable has considerable advantages compared to other types of turntable, in which electrical energy is used to power a motor which actuates the rotation of the tool-holding disk in order to change the tool, hydraulic or pneumatic energy is used to cause the activation of the means of locking and unlocking the member to lock and unlock the tool-holding disk.

It is known to discourage the use of tools using two different types of energy to actuate the tool holder turret, as this requires the provision of all of the necessary access from the energy source to the machine tool on which the turret operates.

However, as described in IT 1,138,598, the mechanisms used by these prior art turrets to stop the angular movement of the disc when the turret reaches a new tool position include pins which snap into corresponding notches when there is a notch in front of the pin as the disc rotates, and since the notches correspond to the intended tool position, the electrical control means gives a release command to the electromagnet connected to the pin.

Due to the inertia of the rotating mass of the tool-holding disk, impacts and consequent oscillations are generated around the selected stop position, which impacts limit the rotation speed, and therefore damping members need to be provided in any case, which increase the complexity of the turret structure and increase the costs.

In particular, the limitation of the rotation speed involves a long tool positioning time, which will affect the machining time.

In order to reduce the tool positioning time and increase the throughput of the machine, servo-controlled turntables equipped with hydraulic locking and unlocking systems have been developed in the prior art.

However, although these solutions have proven to be somewhat efficient in operation, they are still less cost effective because they require two energy supply modes: a power source for rotation and a hydraulic source for locking and unlocking the tool-holding chuck.

Providing two modes of energy supply involves some structural complexity of the distribution wiring connected to the stations and also involves heat dissipation problems.

For example, in order to use a single energy source, in particular electricity, and to simplify the mechanism for stopping the tool holding disks when changing the tool position, as described in WO 2009/012875, it has been proposed to use two electric servomotors, i.e. a first motor for the angular displacement movement of the disks to change the tool position and a second servomotor for the movement by the cam member to lock and unlock the tool holding disks.

However, as described in WO 2009/012875, the use of a second servomotor means that it must be equipped with its own electronic control/command means in addition to those required for the servomotor for the angular movement of said disc, which would significantly increase the cost of the turntable and also expose the turntable to possible malfunctions, such as the failure or erroneous operation of its components.

Disclosure of Invention

It is therefore an object of the present invention to provide a tool holder turret as follows: the tool holder turret employs an electric servo motor designed for angular displacement of the disc to change the tool position and for locking and unlocking the tool holding disc, without suffering from the disadvantages encountered with the prior art turrets described above.

Another object of the invention is to provide a technical arrangement as follows: the technical arrangement for locking and unlocking a tool-holding disk of a turntable, which technical arrangement can provide an optimized utilization of the performance of the electric servo motor in terms of disk displacement speed upon unlocking of the disk, without increasing the overall cost of the turntable and without negatively affecting the operational reliability of the turntable.

These and other objects, as will be explained in more detail below, are achieved by a tool holder turret as claimed in claim 1.

Drawings

The invention will now be described in more detail with reference to a specific preferred embodiment thereof, given by way of example and not limitation and illustrated in the accompanying drawings, in which:

figure 1 shows a longitudinal section of a turntable of the present invention with a tool holding tray in a locked state relative to a fixed base body;

figure 2 shows a longitudinal section of the turret of the invention, with the tool-holding plate in an unlocked state with respect to the fixed base body and free to rotate to change the tool position;

FIG. 3 shows a view of a partial cross-section taken along line III-III of FIG. 1, the partial cross-section being transverse to the axis of rotation of the tool holding tray;

figure 4 shows a view, taken along the line IV-IV of figure 1, of a partial cross section transverse to the rotation axis X-X, with the turntable in the locked position;

fig. 5 shows a view similar to the partial cross-section in fig. 4, taken along the line IV-IV in fig. 2, with the turret unlocked and adapted to change the tool position;

figure 6 shows a rectilinear development of the position taken in the vicinity of the cam profile of the first cylindrical annular body and the cam follower of the second cylindrical annular body, with the turntable in the locked position;

figure 7 shows a rectilinear development of the positions taken in the vicinity of the cam profile of the first cylindrical annular body and the cam follower of the second cylindrical annular body, in a condition in which the turret is in the unlocking position and is suitable to rotate to change the tool position;

fig. 8 shows a longitudinal section of a turntable in a modified embodiment of the present invention in which an electric servo motor is offset from the axis of a tool holding disk in a state in which the tool holding disk is in a locked state with respect to a fixed base body;

fig. 9 shows a longitudinal section of a turntable similar to the turntable in fig. 1, except that a first cylindrical annular body connected to the shaft of the tool holding disk is coupled to an end of a second cylindrical annular body at the front of the first cylindrical annular body.

Detailed Description

With reference to the above figures, numeral 1 indicates a fixed base body of the turret, which defines an internal cavity 2 extending along a longitudinal axis X-X coinciding with the rotation axis of the shaft 3, at the end 4 of which shaft 3a tool-holding disc 5 is fixed, indicated as a whole with 5 a.

As shown, the shaft 3 preferably has an axial cavity 3a, the cavity 3a being used to pass an electric, hydraulic, pneumatic line or mechanical transmission designed to actuate any conventional rotary tool or mechanical device on the tool-holding plate 5.

As described in more detail below, the electric motor, i.e. the electric servo motor 6, controls the shaft 3 in both rotational directions to move the tool holding disk 5, the electric servo motor 6 also serving, according to the invention, to unlock the tool holding disk 5 and subsequently lock the tool holding disk 5 when the tool holding disk 5 is angularly displaced to a different tool position.

The turret comprises a locking member for stably positioning the turret in any working position of the tool.

As known in the art, these locking members comprise: a first toothed ring or gear 10, said first toothed ring or gear 10 being carried by an annular body 11, said annular body 11 being rigidly connected to the base body 1 of the turntable; a second toothed ring or gear 12, the second toothed ring or gear 12 being coaxial with the first toothed ring or gear 10 and being carried by an intermediate plate 13 having a central opening 13a, the intermediate plate 13 being rigidly connected to the tool-holding disk 5 on the side facing away from the tool-mounting face; and a third ring gear or pinion, indicated at 14.

The toothed ring 14 is carried by a first cylindrical annular body 15, the first cylindrical annular body 15 being coaxial with the shaft 3 and able to move axially on the shaft 3, but the first cylindrical annular body 15 is prevented from rotating due to the splined engagement. The toothed ring 14 faces the toothed ring 10 and the toothed ring 12 with a radial extent that engages the toothed ring 10 and the toothed ring 12 when said first cylindrical annular body 15 is axially displaced in the turret locking position.

By using the cam profile 17 it is possible to obtain: against springs 16, the first cylindrical annular body 15 is axially displaced and therefore actuates the locking members so as to be displaced from a locking position, as shown in fig. 1, to an unlocking position, as shown in fig. 2, and from said unlocking position to said locking position, wherein the cam profile 17 is carried at the front by a second cylindrical annular body 20 and is engaged with a cam follower, for example in the form of a roller 18 mounted to said first cylindrical annular body 15 by means of a pin 19. A second cylindrical annular body 20 is also mounted to the shaft 3 and is able to rotate about the axis X-X.

For this purpose, the second cylindrical annular body 20 is connected to a flanged end 21 of a shaft 22 of the servomotor 6 by means of a plurality of peripherally arranged screws 23.

A preloaded axial biasing member in the form of a belleville spring 24 is interposed between the second cylindrical annular body 20 and the flanged end 21 of the drive shaft 22 and abuts an axial shoulder 25 formed in the shaft 3.

In the example shown, the belleville springs are concentric with the shaft 3 of the tool-holding disk 5 and their preload force can be adjusted by inserting spacers in the form of shims 26 and thrust bearings 27.

With particular reference to fig. 6 and 7, it should be noted that the cam profile of the second cylindrical annular body 20, generally designated 17, comprises a planar portion 17a and a plurality of cavities 17b, each cavity 17b having a flat bottom 17c and being recessed below the plane of the planar portion of the cam profile. The side 17d of each cavity is inclined and symmetrical about the center line of the flat bottom, and the side 17d is connected to the planar portion 17 a.

The cam follower elements, i.e. the rollers 18, are preferably arranged on the first cylindrical annular body 15, preferably at the vertices of an equilateral triangle, or alternatively at the vertices of a regular hexagon with the same arrangement as those cavities 17b of the cam profile 17. When these elements engage, at their front portions, with the respective flat portions 17a of the cam profile 17, they keep the first cylindrical annular body 15 axially biased towards the tool-holding disk 5 against the springs 16 and insert the gear 14 into the front gear 10 and the gear 12, while the second cylindrical annular body 20 is axially biased against the shoulder 25 by thrust bearings 27, spacers 26 and belleville springs 24, as shown in figure 6.

Thus, as shown in FIG. 1, the tool-holding plate is in its locked position under the preload force of the Belleville spring 24.

Conversely, when the second cylindrical annular body 20 rotates in either direction as indicated by the arrow of fig. 6 and 7 in response to the command of the servomotor 6, the second cylindrical annular body 20 is angularly displaced around the shaft 3 and the rollers 18 move horizontally to the respective cavities 17b and sink towards the bottom to come into contact with the side 17d, allowing the first cylindrical annular body 15 to move axially under the action of the springs 16.

This axial movement disengages the gear 14 from the gear 10 and the gear 12, thereby releasing the tool holding disk 5 so that the tool holding disk 5 is free to undergo angular movement to change the tool position, as described above.

With reference to fig. 4 and 5, it should be noted that the second cylindrical annular body 20 has, on the front surface facing the first cylindrical annular body 15, a rib 28, said rib 28 projecting axially towards the tool-holding disk 5 and extending over a given arc β of circumference.

Likewise, the first cylindrical annular body 15 coupled to the shaft 3 connected to the tool-holding disk 5 has a front shoulder 29, said front shoulder 29 facing the second cylindrical annular body 20 and extending over a given arc α of circumference, the circumference of the front shoulder 29 of the first cylindrical annular body 15 radially coinciding with the circumference of the rib 28 of the second cylindrical annular body 20 in the arc of circumference not occupied by this rib 28.

The

circumferential ends

30 and 31 of the ribs 28 and the

circumferential ends

32 and 33 of the shoulders 29 define respective abutments which, when engaged together, are adapted to transmit the angular displacement produced by the servo motor 6 to the shaft 3 and hence the angular movement of the tool gripping disc 5 to change the tool position.

As shown, referring to fig. 5, once the second cylindrical annular body 20 has undergone a clockwise angular displacement, the circumferential end 30 abuts the circumferential end 32 and will allow the first cylindrical annular body 15 to move axially and release the front gear 14 from the gear 10 and the gear 12 and set the tool gripping disk 5 in the unlocked state so that the tool gripping disk 5 can rotate to change the tool position.

In the event of an angular displacement of the second cylindrical annular body 20 in the anticlockwise direction, the end 31 of the rib 28 will abut the end 33 of the shoulder 29, allowing the angular displacement of the disc 5 when unlocked.

The first cylindrical annular body 15 has at least one peripheral cavity, indicated 34, which engages at least one tooth 35 formed at the end of an auxiliary tubular shaft 36.

The cavities 34 and teeth 35 are mutually engaged and rotatably engaged and are capable of relative axial translation.

In the example of fig. 1, the auxiliary tubular shaft 36 is oriented coaxially with the axis X-X of the shaft 3 of the tool-holding disk 5 and coaxially with the servomotor 6 shaft 22.

An electromagnetic brake, generally designated 38, which may be a friction brake or preferably a brake with front teeth, is mounted to the end 37 of the shaft 36 opposite the end with the teeth 35 and the cavity 34, for example by means of conventional screws, generally designated 39.

When this brake is applied, it locks the rotation of the shaft 36 and therefore keeps the first cylindrical annular body 15 in the locked rotation state by means of the teeth 35 and the cavity 34, thus also locking any angular displacement of the shaft 3 and of the tool-holding disk 5.

Conversely, when the electromagnetic brake is closed, the shaft 36 can rotate freely, and the first cylindrical annular body 15 can also rotate freely, in the condition in which the cavity 34 is engaged with the teeth 35.

The above description clearly shows that the single electric servomotor 6 is able to unlock the tool holding plate 5 and that once the tool holding plate 5 is unlocked, the single electric servomotor 6 is able to impart the required angular displacement of the tool holding plate 5 by simultaneous frontal engagement between the ribs 28 and the shoulders 29 to bring the tool holding plate 5 to different tool positions. This is possible because the electromagnetic brake 38 is switched off and the shaft 3 can rotate jointly with the second cylindrical annular body 20, the second cylindrical annular body 20 previously unlocking the

gears

14, 10 and 12 that lock the tool-holding disks by acting on the first cylindrical annular body 15.

Once a new tool position is reached and the electromagnetic brake 38 has been activated, the servomotor 6 reverses its direction of rotation and imparts an angular displacement to the second cylindrical annular body 29, the cam profile 17 of the second cylindrical annular body 20 interacting with the cam follower roller 18 of the first cylindrical annular body 15, causing only an axial displacement of said first cylindrical annular body 15 towards the tool-holding disk 5, inserting the toothed wheel 14 into the front

toothed wheels

10 and 12 and causing the tool-holding disk 5 to be locked again.

Structural modifications can be made to the turret, including the position of the servomotor 6, similar to the example of fig. 8, the servomotor 6 can be offset with respect to the axis X-X of the shaft 3 of the tool-holding disk 5 and preferably oriented parallel to the axis X-X, under the intervention of a transmission unit with reduction.

Further, as shown in fig. 9, the first cylindrical annular body 15 connected to the shaft 3 of the turntable may be formed without a front shoulder 29 facing the second cylindrical annular body 20, and the second cylindrical annular body 20 may be formed without the rib 28.

By such a structure, the angular displacement caused by the servomotor 6 is transmitted directly to the shaft 3 of the tool-holding disk, thanks to the engagement between the roller 18 of the first cylindrical annular body 15 and the cam profile 17 of the second cylindrical annular body 20.

Other structural modifications, not shown, may be related to the position of the belleville springs 24 and their preload condition without departing from the scope of the invention as described above and claimed below.

Claims

1. A tool holder turret, the tool holder turret comprising:

a fixed base body (1), said fixed base body (1) having a first cavity (2) extending along a longitudinal axis (X-X);

a tool-holding disk (5), said tool-holding disk (5) being rotatable in two directions of rotation relative to said fixed base body (1) about a rotation axis coaxial and coincident with said longitudinal axis (X-X), said tool-holding disk (5) being mounted to the end of a shaft (3) extending along said longitudinal axis (X-X);

a first cylindrical annular body (15), said first cylindrical annular body (15) being keyed to said shaft (3) and free to slide axially on said shaft (3) only between a first axial position and a second axial position, against elastic means (16) acting between said first cylindrical annular body (15) and said tool-holding disk (5);

a second cylindrical annular body (20), said second cylindrical annular body (20) also being keyed to said shaft (3) and being rotatable with respect to said shaft (3), said second cylindrical annular body (20) having a plurality of symmetrical cam profiles (17, 17a, 17b, 17c, 17d) arranged on the circumference of a front surface of the second cylindrical annular body (20) proximal with respect to said tool-holding disc (5);

-locking means (14, 10, 12), said locking means (14, 10, 12) for locking said tool gripping disc (5) with respect to said fixed base body (1) when said first cylindrical annular body (15) is in a first axial position of said first cylindrical annular body (15) and for unlocking said tool gripping disc (5) when said first cylindrical annular body (15) is in a second axial position of said first cylindrical annular body (15), said first cylindrical annular body (15) having a plurality of cam followers (18), the front faces of said plurality of cam followers (18) being in engagement with respective symmetrical cam profiles (17, 17a, 17b, 17c, 17d) of said second cylindrical annular body (20), said cam followers and said cam profiles causing said first cylindrical annular body (15) to rotate on said axis (3) Axially move in two directions; and

an electric servo motor (6), the electric servo motor (6) being kinematically connected to the second cylindrical annular body (20) to impart an angular displacement to the second cylindrical annular body (20) in two directions of rotation coaxial to the shaft (3),

characterized in that said first cylindrical annular body (15) is kinematically connected (34,35) to a tubular auxiliary shaft (36), said auxiliary shaft (36) being coaxial with said shaft (3) and having braking means (38) to lock the rotation of said first cylindrical annular body (15) when activated.

2. Tool holder turret according to claim 1, characterized in that said second cylindrical annular body (20) has a rib (28), said rib (28) projecting axially towards said tool-holding disc (5) and extending over a given first arc (β) of circumference, said shaft (3) connected to said tool-holding disc (5) being coupled to said first cylindrical annular body (15) having a front shoulder (29), said front shoulder (29) facing said second cylindrical annular body (20) and extending over a given second arc (α) of circumference, the circumference of said front shoulder (29) coinciding radially with the circumference of said rib (28) projecting axially outwards from said second cylindrical annular body (20) in the portion of arc not covered by said rib, the circumferential ends (30, 31) of said rib (28) and the circumferential ends (32, 33) of said shoulder defining respective abutments, such that when said abutments are in mutual engagement they are adapted to transmit the angular displacements of the shaft (3) generated by said servomotor (6).

3. The tool holder turret according to claim 1, wherein the locking member comprises:

a first toothed ring (10), said first toothed ring (10) being carried by said fixed base body (1) and being arranged around said longitudinal axis (X-X) of said first cavity (2);

a second toothed ring (12), said second toothed ring (12) being concentric to said first toothed ring and being carried by said rotating tool-holding disk (5); and

a third toothed ring (14), said third toothed ring (14) being fixed to an axial end of said first cylindrical annular body (15) facing said tool-holding disk (5).

4. Tool holder turret according to claim 1, wherein said braking means (38) is an electromagnetic brake coupled to an end (37) of said auxiliary shaft (36), said auxiliary shaft (36) being kinematically connected to said first cylindrical annular body (15).

5. The tool holder turret according to claim 1, wherein each of the symmetrical cam profiles comprises a second cavity (17b), the flat bottom (17c) of the second cavity (17b) being lower than a reference plane (17a), and the side (17d) of the second cavity (17b) comprises a straight section symmetrically inclined to the flat bottom (17c) of the second cavity.

6. Tool holder turret according to claim 1, wherein said cam followers comprise rollers (18), said rollers (18) being free to rotate around respective pins (19), said pins (19) being carried by said first cylindrical annular body (15), the periphery of said rollers contacting respective said cam profiles carried by said second cylindrical annular body (20).

7. The tool holder turret according to claim 1, wherein the first cylindrical annular body (15) has at least one third cavity (34) on a peripheral surface thereof, the tubular auxiliary shaft (36) having at least one tooth (35), the tooth (35) rotatably engaging the third cavity (34) and being axially translatable relative to the third cavity (34).

8. The tool holder turret according to any of claims 1 to 7, comprising a preloaded axial biasing member (24), said preloaded axial biasing member (24) being located between said second cylindrical annular body (20) and a stop member (25), said stop member (25) being constituted by an axial shoulder formed in said shaft (3).

9. The tool holder turret according to claim 8, wherein the preloaded biasing member is a disc spring (24), the disc spring (24) being positioned concentrically with the shaft (3) of the tool holding disc (5), the stop member being adjustable by the insertion of a spacer (26) to impart a desired preload force to the disc spring.

10. Tool holder turret according to any of claims 1 to 7, wherein the axis of rotation of the electric servo motor is positioned coaxially with the axis of rotation (3) of the tool holding disc (5).

11. Tool holder turret according to any of claims 1 to 7, characterized in that the axis of rotation of the electric servo motor (6) is offset with respect to the axis of rotation (3) of the tool holding disc (5) and is connected to the tool holding disc (5) by means of a kinematic member (60) interposed between the tool holding disc (5) and the electric servo motor (6).

12. Tool holder turret according to claim 5, characterized in that it is adapted to transmit the angular displacement generated by said electric servo motor (6) to said shaft (3) of said tool holding disc (5) when said cam follower (18) carried by said first cylindrical annular body (15) contacts said side (17d) of said cam profile (17b) carried by said second cylindrical annular body (20) and when said first cylindrical annular body (15) is under a predetermined spring preload force (16).